text: Calthemite rimstone or gours can form beneath concrete structures on a floor with a gradual sloping surface or on the side of rounded stalagmites. When the leachate drip rate is more frequent than 1 drop per minute, most of the calcium carbonate is carried by the leachate from the underside of the concrete structure to the ground, where stalagmites, flowstone and gours are created. The leachate that does reach the ground usually evaporates quickly due to air movement beneath the concrete structure, hence micro-gours are more common than larger gours. In locations where the deposition site is subject to abrasion by vehicle tyres or pedestrians traffic, the chance of micro-gours forming is greatly reduced.